Why does JBT use the different Position Sizing in differemt modes?

[just4look]

In PortfolioManager, there is code

    public int getSize(Strategy strategy) {
        Mode mode = dispatcher.getMode();
        if (mode == Mode.BackTest || mode == Mode.Optimization) {
            return 1;
        }
        int maxOpenPositions = strategy.getMaxOpenPositions();
 
        ..........

Why does JBT use the different Position Sizing in differemt modes?

Thanks